Limp mode is a protective mode the engine or transmission computer switches to when it detects a fault that could cause damage. It cuts power, limits engine speed and often holds the transmission in a single gear, usually with a warning light, so you can drive slowly to safety without making the problem worse. The cause can be anything from low transmission fluid or a failed solenoid to a faulty sensor or a boost problem.
Limp mode symptoms
- A sudden loss of power and a low engine speed limit
- The transmission stuck in one gear, often second or third, or refusing to upshift
- A check engine or transmission warning light, sometimes with a message on the dash
- Accessories such as the air conditioning switched off to reduce load
Common causes of limp mode
Transmission problems
Low or burnt fluid, a failed shift or pressure control solenoid, a faulty speed sensor, wiring faults or a failing transmission control module. See transmission solenoid symptoms and transmission slipping: signs and causes.
Engine sensors and throttle
A faulty throttle position, accelerator pedal, mass airflow or manifold pressure sensor, or a problem with an electronic throttle body, can make the computer limit power because it can no longer trust its readings.
Boost problems
On turbocharged and supercharged engines, too much or too little boost, a boost leak or a sticking turbo control can trigger limp mode.
Overheating and electrical faults
An overheating engine or transmission, low battery voltage, a bad ground or corroded connectors can all set off protective modes. On diesels, faults in the emissions system can also reduce power until they are repaired.
What to do if your car goes into limp mode
- Get somewhere safe at low speed and switch off the engine.
- Check the basics: engine oil, coolant and, where you can, transmission fluid level and condition; our how to check transmission fluid guide explains how.
- Restart: limp mode sometimes clears after a restart, but the fault that caused it is usually still there and will come back.
- Read the codes with a scan tool; they point to the system that triggered it.
- Repair the cause rather than clearing codes and driving on.
Can you drive in limp mode?
Only as far as you need to reach home or a repair shop, gently and at low speed. Limp mode exists to protect the engine and transmission; driving hard or for long distances in it can turn a small repair, such as a sensor or a fluid top-up, into a major one.
When the transmission is the problem
If the codes point to internal transmission damage, compare a repair with a replacement unit. We carry automatic transmissions for Chevy, GMC, Ford and Dodge/Ram vehicles, each supplied with a torque converter, listed by code on our transmissions page. What transmission do I have? helps you find your code.
More guides: check engine light · bad alternator symptoms · reduced engine power · transmission range sensor · why a 4L60E limps in third gear · why a 68RFE limps in second gear · transmission won’t shift · transmission overheating · car loses power when accelerating · car won’t move in drive · why a 545RFE limps in second gear · bad TCM symptoms · bad transmission speed sensor symptoms.
Trouble codes: P0700 Transmission Control System · U0101 Lost Communication With TCM · P2135 Throttle Position Sensor Correlation · P0730 Incorrect Gear Ratio · P0299 Turbo/Supercharger Underboost · P0868 Transmission Fluid Pressure Low · P0716 Input/Turbine Speed Sensor Range · P0780 Shift Error · P0641 Sensor Reference Voltage A · P0642 Sensor Reference Voltage A Low · P0702 Transmission Control Electrical · P2119 Throttle Body Range/Performance · P2127 Pedal Position Sensor E Low · P0243 Wastegate Solenoid A · P0745 Pressure Control Solenoid A · P0884 TCM Power Input Intermittent · all OBD2 codes.
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